Serena Williams lashed out against the umpire during her U.S. Open tennis final against Naomi Osaka after he accused Williams and her coach of illegally communicating during the match on Saturday. Williams ultimately lost the Grand Slam tournament to Osaka.

During the match, umpire Carlos Ramos issued several violations against Williams. In the first violation, Ramos accused Williams of receiving coaching from her coach, Patrick Mouratoglou, who was in the stands. Mouratoglou had apparently motioned for Williams to go to the net more often.

The second violation was issued after Williams broke her tennis racket in frustration, which led to a point penalty. Ramos issued a third violation, which included a game penalty, after Williams confronted him and called him a “thief.”

“You stole a point from me,” she said. “You’re a thief.”

After Ramos issued the first coaching violation, Williams approached the umpire chair and calmly defended herself.

When she received a point reduction for breaking her racket, she confronted Ramos again.

“You owe me an apology,” she told the referee. “I have never cheated in my life. I have a daughter and I stand for what’s right for her. I’ve never cheated, and you owe me an apology. You will never do another one of my matches.”

Later, speaking to referee Brian Earley and Women’s Tennis Association official Donna Kelso, Williams said the violations Ramos issued against her don’t happen to male players.

“There’s a lot of men out here that have said a lot of things and because they’re a man, that doesn’t happen to them,” she told the officials.